Use Scanner and Scanner.nextInt() method to take only Integer as input from the user.

Scanner sc = new Scanner(System.in);
int anyNumber = sc.nextInt();

If the user gives an input which is not an integer, it will throw an InputMismatchException.

You can use java.util.Scanner (API):

import java.util.Scanner;

//...

Scanner in = new Scanner(System.in);
int num = in.nextInt();

It can also tokenize input with regular expression, etc. The API has examples and there are many others in this site (e.g. How do I keep a scanner from throwing exceptions when the wrong type is entered?).

int speed = Integer.parseInt(System.console().readLine());

Not sure how old that book is but this should be the correct way of doing it. As far as I know readInt isn't a function of console.

Integer.parseInt(String); is something that you want.

Try this:

int[] array = new int[size];
    try {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        for (int j = 0; j < array.length ; j++) {
                int k = Integer.parseInt(br.readLine());
                array[j] = k;
        }
     }

    catch (Exception e) {
            e.printStackTrace();
     }

Anyways,why don't you use Scanner? It'd be much easier for you if you use Scanner. :)

int[] array = new int[size];
    try {
        Scanner in = new Scanner(System.in); //Import java.util.Scanner for it
        for (int j = 0; j < array.length ; j++) {
                int k = in.nextInt();
                array[j] = k;
        }
     }
     catch (Exception e) {
            e.printStackTrace();
     }

Try the following:

Scanner scanner = new Scanner(System.in);

System.out.print("Enter some integer:\t");

int myIntValue = scanner.nextInt();

In order to use through the lifespan of your test application, you can do the following:

public void scanInput() {

    Scanner scanner = new Scanner(System.in);

    while (true) {
        System.out.print("Enter some integer:\t");
        int myIntValue = scanner.nextInt();
        System.out.print("You entered:\t" + myInteValue);
    }
}

You need something like a scanner to read-in values from console. The code should look like that:

import java.util.Scanner;

class TUI {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.println("Enter the two numbers:");
        System.out.println("Enter n1:");
        int n1 = scanner.nextInt();
        System.out.println("Enter n2:");
        int n2 = scanner.nextInt();
        int total = n1 + n2;
        System.out.println("Total is =" + total + ".");
        scanner.close();
    }
}

I hope it helps.